It almost sounds too good to be true. By placing a couple of tinted plastic filters over the page he's reading, Eric Johnson, a 25-year-old dyslexic, can double his reading speed. Words that were once fuzzy now snap into focus. Halos that once shadowed the letters disappear.

"I'm able to concentrate longer on the words, read faster and for a longer period of time," said Mr. Johnson, an undergraduate at the University of Maryland at College Park. Without the three 8 1/2 -inch-by-11-inch overlays, Mr. Johnson can focus on only a few words at a time.

Mr. Johnson's experiences would come as no surprise to Helen Irlen. A Long Beach, Calif., psychologist, Mrs. Irlen has promoted the use of tinted filters and lenses for dyslexics since the early 1980s. But her techniques have been regarded with suspicion, largely because some researchers and doctors could see no scientific basis for them.

Now, however, new research showing that dyslexics have a defect in the brain's visual system is focusing increased attention on Mrs. Irlen's methods. Yet people in the field of dyslexia continue to question the effectiveness of the lenses, as well as their high cost.

At the heart of the debate is a recent study in which a team of Harvard Medical School brain researchers reported that certain visual systems of dyslexics are more sluggish in processing stimuli than those of non-dyslexics. They also discovered that the cell bodies making up those systems are smaller in dyslexics than in those without the disorder.

Dyslexia, which is thought to affect some 12 million Americans, is typically associated with symptoms such as poor spelling, great difficulty learning to read and reversal of symbols in reading, writing and math. The disorder has nothing to do with intelligence.

Traditionally, dyslexia was seen as a malfunction in the way people understand language, without a visual component, according to Dr. Albert M. Galaburda, a Harvard University neurologist who took part in the study. But both this study, described in the Sept. 15 issue of the scientific journal Proceedings of the National Academy of Sciences and recent research on the auditory systems of dyslexics by Dr. Paula Tallal, a professor at the Rutgers Center for Molecular and Behavioral Neurosciences, points to the theory that dyslexics have several brain defects that hamper their sight.

"This research confirms a lot of our findings," said Ms. Irlen, whose 52 clinics around the world have prescribed tinted lenses for approximately 20,000 people, at the cost of about $400 a pop. "People didn't understand why [the lenses] worked, but this shows why you need to filter the speed or frequency of light."

According to Dr. Bruno Breitmeyer, a professor of psychology at the University of Houston who has conducted extensive research on dyslexia, timing of the visual systems plays an important role in a person's ability to read without words blurring, fusing or jumping off a page -- a frequent complaint of dyslexics. The Harvard study indicates that dyslexics' systems operate with a different timing than those of non-dyslexics.

Mrs. Irlen, who first outfits clients with a set of plastic overlays, then with the colored lenses, has claimed that one-third of those who use the lenses are left with no symptoms of dyslexia. She also says that the lenses work by combating scotopic sensitivity syndrome, a sensitivity to certain wavelengths of light which is thought to be common among dyslexics.

But many who work in the field of dyslexia caution against leaping to conclusions about the lenses.

Much of the skepticism centers around the preliminary nature of the study performed by the Harvard researchers -- only 10 living people were tested and only 10 brains examined -- as well as the lack of research available on use of the lenses.

"Our position is simply that we are concerned that when a study that deals with a very small handful of people, people are going to make a leap of faith to say that [the lenses] are the answer," said Rosemary Bowler, executive director of the Orton Dyslexia Society, a national organization that is headquartered in

Baltimore. "The jury is still out on the effectiveness of these kinds of treatments."

Ms. Bowler did not completely reject use of the lenses, however. "Anything that's going to make people more comfortable, easier for them to function, is certainly worth exploring," she said. But, she added, the necessity of using other approaches to treat dyslexia still exists. "The implication is that if you go out and spend $400, $500, $600 [on lenses], something magical is going to happen. It may help you. But it won't obviate the need for some very long-term, sometimes not terribly exciting educational intervention."

The traditional technique of educating dyslexics is a multisensory approach in which they learn to read by seeing words, hearing them and tracing letters with their fingers -- rather than just by sight.

Kathy Kesler, headmistress of the Valley Academy, a secondary private school in Towson whose student population is largely made up of dyslexics, also voiced skepticism about Mrs. Irlen's methods. "People are always trying to find something new and to get on the bandwagon and find a new fix, because the other way is hard work," she said. But she has not found that using colored filters while tutoring students results in a marked improvement in reading skills. One student who obtained Irlen lenses felt they aided his reading, but he remains dyslexic and still needs special education.

According to Martha Bridge Denckla, a professor of neurology and pediatrics at the Johns Hopkins University School of Medicine, visual disturbances may constitute a part of dyslexia, but the disorder primarily involves trouble with the speech-sound part of language. A typical dyslexic child, for example, would have difficulty transforming an ordinary spoken sentence into pig Latin -- an exercise that has nothing to do with vision.

Others criticize the cost of the lenses. "I think it's criminal that they sell these [lenses] for $500, and no one's done a controlled study on them," said Margaret Livingstone, the Harvard neuroscientist who led the study examining dyslexics' visual systems. "There's something very suspicious about that. Before they charge people so much money, they should have a study." Her own study did not test the lenses, she noted, although its results were "not inconsistent with their effectiveness."

Meanwhile, Mrs. Irlen responded by claiming that the charge for the screening process and determining the correct lense color for each individual was "very reasonable," considering that the process takes between six and eight hours.

"There's a resistance within certain communities for charging money," said Mrs. Irlen. "Anything that has a fee connected with it will be looked at in disrepute. But there's no way around the cost when there's the time that has to be put into doing the diagnostic process."

For Eric Johnson, the testing was well worth the time and cost. "I could read, but it was always torture for me," the Montgomery County native said. "I remember not being able to focus on words, and the whole paragraph or page being fuzzy."

With his blue-gray tinted lenses, Mr. Johnson, who is majoring in marine biology, no longer has to reread passages many times. "I'm not losing my place and my focus the way I used to," he said.

Others have found the devices far less effective. After seeing a television program on the Irlen lenses two years ago, Susan Tosato of Harford County had her 8-year-old dyslexic son outfitted with a pair. But she saw almost no change in R. J.'s reading. He stopped wearing the dark blue glasses about six months after getting them.

"I feel like I was gypped," said Ms. Tosato, who claimed she paid about $1,000 for the testing and the lenses. "For the amount of money it cost, it sure wasn't worth it."

Mrs. Irlen shrugs off such reports. "This is a piece of the puzzle for some individuals," she said. "It's not going to be the answer for every individual. But for those for whom it's an answer, it's significant, because there's no other technique out there which can do this."

For further information about dyslexia, call the Orton Dyslexia Society 296-0232 or (800) 222-3123.

Symptoms of dyslexia

* Inconsistency in academic performance.

* Frequent letter reversals: rotations and/or transpositions in reading, writing and/or spelling.

* Inability to read satisfactorily in spite of adequate intelligence and educational opportunity.

* Unusual difficulty with spelling beyond the weekly spelling test.

* Auditory discrimination problems: sometimes confusing similar speech sounds.

* Unusual difficulty with handwriting.

* Difficulty remembering how to make better shapes.

* Difficulty copying accurately from close up, far away or both.

* Written work that does not reflect the student's potential.

* Difficulty completing written assignments.

* Inability to recite the alphabet correctly in sequence (without singing or chanting).

* Inability to write the alphabet correctly in sequence.

* Poor recall ability, especially for words and names.

* Difficulty with clear and fluent expression.

* Poor organizational skills.

* Forgetting assignments and/ or losing papers frequently.

* Directional confusion and/or difficulty with spatial orientation -- such as left/right, before/after or under/over.

* No established preference for right or left hand for writing.

* Being overly active and disturbing; or unusually passive and withdrawn most of the time.

* Short attention span.